Improvement in dental foil



UNITED STATES PATENT Orrrcn.

RICHARD S. WILLIAMS, OF NEW YORK, N. Y.

IMPROVEMENT- IN DENTAL FOIL.

Specification forming part of Letters Patent No. 172,8 [2, dated January25, 1876; application filed November 16, 1875.

/ y OAsE B.

' provement in dental foil; and the invention consists in dental foil towhich a small percentage of tin has been added, to take from it itscohesive properties after annealing, and,

therefore, be more easily manipulated by th dentist.

The well-known property inherent in pure gold of cohering after it isannealed renders it difficult for dentists, in some cases, to properlyprepare it for use, since the cohering of the surfaces, when it isfolded and rolled, renders the gold stiff, or, as it-is termed, hard. Toprevent this,'and to enable the gold to fold or roll up soft, I takepure gold, add to it a small proportion of pure tin-say, onehalf agrain, or" less, of pure tin to nine hundred and ninety-nine andone-half grains of pure gold. These proportions may be slightly alt red;but the proportions lhave named will give excellent results.

The gold, being in this way alloyed, seems to have its tenacityincreased; but the chief result obtained is that the surfaces of foilprepared from such alloyed gold, after it is annealed, will not adhere,but will, as it were, slide on each other, unless considerable pressureis used. Hence, foil made from gold in this way alloyed maybe readilyfolded or rolled, and yet the rolls or folds will be plia- Me and easilyworked.

This result is produced by the heat used in annealing the foil, thisheat slightly oxidizing the tin on the surface of the foil. This oxideis sutlicient tokeep the surfaces of the gold from coming in such closecontact as to cohere, and, therefore, give all the advantages ofannealed gold without the disadvantage of its adhering. But when it isdesired that this gold shall adhere, as when filling a cavity, then theforce with which it is pressed into the cavity will be sufficient tocause it to cohere, forming a solid mass, the same as the ordinaryannealed gold.

The gold and thetin both being pure, when in use nothing deleterious cancome from the use of the alloy, and hardly any perceptible change ofcolor is noticeable in the gold from the addition of the tin.

It is obvious that the proportions of gold and tin above given may bevaried to some extent without departing from the spirit of my invention,and I, therefore, do not wish {)0 limit myself to the proportions abovegiven Having thus described my invention, what -I claim as new, anddesire to secure by Letters Patent, is- Y As a new article ofmanufacture, dental foil alloyed with tin, substantially as described.

RIOHD. S." WILLIAMS.

Witnesses: H. L. WATTENBERG, G. M. PLYMPTON.

